do you agree with it???

Dear ALL,

Yesterday, my manager told me that I had used a wrong
material to conducted my structural analysis
of a rotating turbine blade (including airfoil,and the disk 
supporting it). He said, however, the predicted stress value based on
the wrong material should be the same as what we can see using the
right
material. Only frequencies and modal shapes need to be re-calculated.

It surprised me a lot!!! Can you guys agree with my manager's 
words? If so, pls. detail the resons. He may have some hints on the
wrong material and right material that we should use, for example,
even they are
different material, but they have very close Densities, and Youngs
modules,
my point is, ideally, the stress will absolutely depend on the
material, right?
can you imagine that a rotating steel turbine and a rotating wooden
turbine have
exactly the same stress?
It is so strange!

This could be a very funny problem, forgive  me if you think so.
thanks,